VIM Vacuum Induction Melting

The Vacuum Induction Melting (VIM)Process

The Vacuum Induction Melting (VIM)Process, initially used to meet alloy requirements of specialised industries, is becoming more and more essential in the production of high performance materials for many industrial applications. VIM melted alloys are used in very demanding situations, including Nickel based super alloys for high temperature applications, stainless steels for nuclear applications, Cobalt based alloy for medical applications, high purity copper alloys and very clean magnetic alloys for high permeability.

The VIM process involves the melting of metals by means of electromagnetic induction while under vacuum. Melting takes place within a furnace consisting of a refractory lining or crucible inside a water-cooled induction coil. The furnace assembly is completely enclosed by a fabricated steel, water cooled furnace chamber that is evacuated by a series of vacuum pumps so that the charge may be melted down, refined and poured into moulds under vacuum or inert gas.

This process permits the refining of metals and alloys that contain elements having a strong affinity for certain gases such as oxygen. Chemical reaction, dissociation and flotation remove dissolved and chemically bonded impurities. Melt chemistry can be accurately adjusted thereby producing an end product that is clean and homogeneous.

Small VIM Furnaces

Consarc have developed a range of VIM furnaces from 2-100 kg (steel) melt capacity for use in small scale production or research applications. Standard designs are available and Consarc also welcome the opportunity to design a specific furnace to meet individual customer requirements and applications.

The design utilises a water-cooled vacuum chamber, providing optimum access for cold charging and servicing in a batch mode of operation. The chamber also houses auxiliary equipment with standard and optional features provided by Consarc to ensure maximum flexibility and ease of operation.

These features can include:

Bulk charging and fine alloy additions
Sample taking
Immersion thermocouple
Mould turntable/trolley for pouring multiple moulds in a single cycle
Centrifugal casting
Sight glass viewing port(s)
High vacuum pumping system
Optical pyrometer
Bridge breaker

Configurations - Side opening & Top opening designs

Horizontal furnaces with front opening access door or Vertical chamber configurations with a top opening lid can be supplied depending on the application and available floor space.

Batch or Semi-continuous

Using a modular design concept enables this range of batch VIM furnaces to be upgraded to a semi-continuous VIM or vacuum precision casting furnace with the addition of a mould chamber at a later date.

Large VIM Furnaces

Consarc has designed and built over half of the large (3 tonnes or more) Vacuum Induction Melting systems in the world. Consarc follows in the tradition of its parent company, Inductotherm, a leader in the induction furnace technology, by meeting exceptional challenges with creative problem solving. By designing highly efficient VIM furnace systems that meet customers' unique needs and exceed their expectations, we have built up an impressive track record.

Configurations Batch or Semi-continuous

Our engineers will design and build a system that is compatible with your process, your alloys, your specifications and the annual tonnage you desire. This could involve a multi-chamber, semi continuous furnace for large operations or a cost effective single chamber batch design for smaller needs.

Applications

Consarc VIM furnaces are primarily used for producing large ingots (electrodes) for remelting and small round bars (master alloy barstock) for precision casting.

Reliability

All Consarc VIM furnaces are efficient, easy to operate and designed for consistent and reliable operation with maximum productivity. They are reliable rugged units that will thrive in even the most demanding factory environment.

Maintenance, Cleaning and Productivity

Consarc Vacuum Induction Melting furnaces are specifically designed for the harsh environment that the VIM process creates. An essential part of the process involves the volatilisation of dissolved gases and harmful metallic trace contaminants. Therefore metallic vapours are created during the refining process and this generates a dusty, hazardous environment inside the melting chamber.

Consarc ensure that the VIM furnace and melting chamber is adequately sized and designed to operate well in this dusty environment and that the furnace can operate for many consecutive melting cycles without the need for comprehensive cleaning between melts. This simple design philosophy ensures that the VIM furnace offers the highest possible productivity in operation. Also when cleaning is required the chamber and surrounding platform are designed to make this a simple, safe operation for operators with appropriate apparatus and safety equipment.

Vacuum System Design

Vacuum pumping systems are designed to provide consistent vacuum performance to suit the individual process requirements. These pumping systems are designed with oil sealed rotary pumps, dry pumps, roots blowers, oil boosters or oil diffusion pumps as required. Steam ejector systems can also be employed on the largest systems.

Material handling and charging systems

Our Vacuum Induction Melting Furnaces offer a variety of materials handling systems for charging (Vertical bucket type chargers and horizontal Vibratory side feeders), sampling, tilting, mould movement, tundish handling and fast removal and replacement of induction melting units with their refractories.

Induction Power Equipment

Melting power is supplied from a solid state Inductotherm induction power supply. It is taken through the vacuum chamber by means of a vacuum sealed power feed through or power port assembly to the melting coil. A specially designed quick change power port allows melting furnace coil assemblies to be rapidly exchanged in the hot condition thereby saving production time and increasing productivity.

Vacuum Isolation Valves

Consarc also design and fabricate our own range of water-cooled isolation valves to accommodate the larger sizes required for larger units.

Hot Tundish Insertion

In most large system designs a hot tundish insertion system is supplied. The hot tundish insertion process allows insertion of a heated tundish without disturbing the vacuum in the melting chamber, thus improving the quality of the product. The tundish is a preformed ceramic launder which incorporates a series of dams, weir and filters with a pouring nozzle at one end. As metal is poured through the tundish, dross and potential inclusions are filtered out ensuring a clean metal stream arrives at the nozzle for smooth pouring into the moulds.

Controls

The Vacuum Induction Melting furnaces incorporate the latest PLC and PC SCADA controls to accurately monitor and control the melting process and provide extensive data acquisition of melt process parameters.